For those of you who spend annoying amounts of time looking for tools, fear no more. Toolboxes for each optical table are coming!
They will probably have:
IR Viewer (a few optical tables will have IR viewers, these specific tables will be labeled in the diagram coming out later)
Ball screw drivers (3/16 in.) 6-8 in. handle
Various Connectors (I'll find out what's needed at some point)
Small flat screwdrivers (for adjusting camera gains)
Please suggest what else may be needed in these boxes.
The boxes will be held to the side of the tables, either by magnets or screws. A diagram of where they will be placed on each optical table in order to minimize obstruction of walkways will be distributed soon. Any objections can then be noted.
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon.
I also took every allen key I can find so they can be sorted. They will be back in the appropriate drawer locations soon.
No, the small boxes must be attached to the optical tables. They won't be heavy enough to change the table tilt.
Also, all tools must be color coded according to the optical table using the 3M Vinyl table color code:
So the new tentative plan on the boxes is to bolt them (magnetic strips were proposed but overruled on the grounds that they're not strong enough to withstand being knocked down by accidents).
The boxes are going to be a mix of the Thorlabs Benchtop Organizer (http://www.thorlabs.com/thorProduct.cfm?partNumber=BT17) and the original box. The box will have a region covered in mesh, so tools can be placed and held there. The box will also have a spacer at the bottom, with another mesh right above it, lined up. However, this double-mesh will only cover half of the box. The other half of the box will be compartmentalized to hold things such as screws, connectors, etc. I will talk to Steve about building the boxes.
Also, using nail-polish to coat the Allen wrenches is not going to work. Nail polish does not stick easily enough. The tentative new plan is oil paint, but this is to be reviewed.
Finally, the diagram with the placement of the boxes relative to the optical tables has been put on paper, but needs to be computerized so it's easier to read. This will be done as soon as possible.
There are some tips for how to appy nail polish on YouTube from MKNails and MissJenFABULOUS. Their tips on how to prepare the site for a strong bonding strength are probably helpful for our gold/nickel coated tools. For chrome tools we may need to abrade the surface with a stone or fine sandpaper for it to take the layer better. IF the YouTube videos don't do it for you, then I suggest contacting Tom Evans at LLO to find out what kind of nail polish he uses.
This is the tentative box placement per optical table. The toolboxes are going to be color-coded by a combination of two colors (the order won't matter). The side of each toolbox will have a little panel to let you know which box corresponds to which set of colors.
On the diagram, the set of colors is simply the color of the box border and the color of the text.
If anyone has a problem with any of the colors or the box placement let me know before they are installed and become an annoyance:
ETMY: Box will be attached to the underside of the table by magnets. The box will be on the north side of the optical table.
POY: Box will be attached to the side of the optical table by magnets. The box will be on the west side of the optical table.
BSPRM: Box will be attached to the side of the optical table by magnets. The box will be on the west side of the optical table.
AS: Box will be attached to the side of the optical table by magnets. The box will be on the north side of the optical table.
PSL1: Box will be inside the optical table, in the northeast corner.
PSL2: Box will be inside the optical table, in the southwest corner.
POX: Box will be attached to the side of the optical table by magnets. The box will be on the south side of the optical table.
MC2: Box will be attached to the side of the optical table by magnets. The box will be on the south side of the optical table.
ETMX: Box will be attached to the side of the optical table by magnets. The box will be on the east side of the optical table.
I decided to go see what the electrical tape looks like on the other tools.
These are the tools I felt were necessary to label with tape: (the others don't seem to be terribly important in terms of not interchanging between boxes)
On another note I'm not sure why electrical tape can't be used on the Allen Wrenches too.
I also plan on ordering smaller flash lights for each table (this one is bulky and unwieldy), and filling in the gaps of the Allen Wrench sets as soon as I get the go-ahead.
I have moved the optical fiber module for FOL to the PSL table. It is setup on the optical table right now for testing.
Once tests are done, the box will move to the rack inside the PSL enclosure.
While doing any beat note alignment, please watch out for the loose fibers at the north side of the PSL enclosure until they are sheilded securely (probably tomorrow morning).
We successfully laid down all required optical fibre fiber cables from 1X4-1X7 region to 1Y1-1Y3 region today. This includes following cables:
With Steve's help, I installed the Oplev earlier today. I adjusted the positions of the two lenses until I deemed the spot size on the QPD satisfactory by eye. As a quick check, I verified using the DTT template that the UGF is ~5Hz for both pitch and yaw. There is ~300uW of power incident on the QPD (out of ~2mW from the HeNe). In terms of ADC counts, this is ~13,000 counts which is about what we had prior to taking the endtable apart. There are a couple of spots from reflections off the black glass plate in the vacuum chamber, but in general, I think the overall setup is acceptable.
This completes the bulk of the optical layout. The only bits remaining are to couple the IR into the fiber and to install a power monitoring PD. Pictures to follow shortly.
Now that the layout is complete, it remains to optimize various things. My immediate plan is to do the following:
I will also need to upload the layout drawing to reflect the layout finally implemented.
Not directly related:
The ETMx oplev servo is now on. I then wanted to see if I could lock both arms to IR. I've managed to do this successfully - BUT I think there is something wrong with the X arm dither alignment servo. By manually tweaking the alignment sliders on the IFOalign MEDM screen, I can get the IR transmission up to ~0.95. But when I run the dither, it drives the transmission back down to ~0.6, where it plateaus. I will need to investigate further.
GV Edit: There was some confusion while aligning the Oplev input beam as to how the wedge of the ETM is oriented. We believe the wedge is horizontal, but its orientation (i.e. thicker side on the right or left?) was still ambiguous. I've made a roughly-to-scale sketch (attachment #1) of what I think is the correct orientation - which turns out to be in the opposite sense of the schematic pinned up in the office area.. Does this make sense? Is there some schematic/drawing where the wedge orientation is explicitly indicated? My search of the elog/wiki did not yield any..
ACAD files of the 40m optical layout have been updated as per the vent in Aug 2011.
Files are available at the 40m svn docs-->Upgrade12-->Opt_Layout2011.
To ease the pain of hunting files, optical layout ACAD files have been moved to a new directory 40M_Optical Layout in the repository. Relevant files from directories Upgrade12 and upgrade 08 will be moved to "40M_Optical Layout" very soon and eventually these old directories will be removed.
Changes mentioned by Koji and Steve have been updated to the files (except for the cable connector which have been added but whose part number has to be found to match accurately with the current layout). The file in the directory should now match the current setup after the last vent Aug 2011.
Let me know if you find any mismatch between the current setup and the layout.
Plans about new installations/reconfiguration during the new vent will be carried out in a separate file.
I disabled the OL loops for ITMX, ITMY and BS at GPStime 1194897655 to come up with an Oplev noise budget. OL spots were reasonably well centered - by that, I mean that the PIT/YAW error signals were less than 20urad in absolute value.
Attachment #1 is a first look at the DTT spectra - I wonder why the BS Oplev signals don't agree with the ITMs at ~1Hz? Perhaps the calibration factor is off? The sensing noise not really flat above 100Hz - I wonder what all those peaky features are. Recall that the ITM OLs have analog whitening filters before the ADC, but the BS doesn't...
In Attachment #2, I show comparison of the error signal spectra for ITMY and SRM - they're on the same stack, but the SRM channels don't have analog de-whitening before the ADC.
For some reason, DTT won't let me save plots with latex in the axes labels...
I bet the calibration is out of date; probably we replaced the OL laser for the BS and didn't fix the cal numbers. You can use the fringe contrast of the simple Michelson to calibrate the OLs for the ITMs and BS.
I've been trying to put together the cost-function that will be used to optimize the Oplev loop shape. Here is what I have so far.
All of the terms that we want to include in the cost function can be derived from:
From these, we can derive, for a given controller, C(s):
We can add more terms to the cost function if necessary, but I want to get some minimal set working first. All the "requirements" I've quoted above are just numbers out of my head at the moment, I will refine them once I get some feeling for how feasible a solution is for these requirements.
An elog with a first pass at a mathematical formulation of the cost-function for controller optimization to follow shortly.
For a start, I attempted to model the current Oplev loop. The modeling of the plant and open-loop error signal spectrum have been described in the previous elogs in this thread.
I am, however, confused by the controller - the MEDM screen (see Attachment #2) would have me believe that the digital transfer function is FM2*FM5*FM7*FM8*gain(10). However, I get much better agreement between the measured and modelled in-loop error signal if I exclude the overall gain of 10 (see Attachments #1 for the models and #3 for measurements).
What am I missing? Getting this right will be important in specifying Term #4 in the cost function...
GV Edit 2 Aug 0030: As another sanity check, I computed the whitened Oplev control signal given the current loop shape (with sub-optimal high-frequency roll-off). In Attachment #4, I converted the y-axis from urad/rtHz to cts/rtHz using the approximate calibration of 240urad/ct (and the fact that the Oplev error signal is normalized by the QPD sum of ~13000 cts), and divided by 4 to account for the fact that the control signal is sent to 4 coils. It is clear that attempting to whiten the coil driver signals with the present Oplev loop shapes causes DAC saturation. I'm going to use this formulation for Term #4 in the cost function, and to solve a simpler optimization problem first - given the existing loop shape, what is the optimal elliptic low-pass filter to implement such that the cost function is minimized?
There is also the question of how to go about doing the optimization, given that our cost function is a vector rather than a scalar. In the coating optimization code, we converted the vector cost function to a scalar one by taking a weighted sum of the individual components. This worked adequately well.
But there are techniques for vector cost-function optimization as well, which may work better. Specifically, the question is if we can find the (infinite) solution set for which no one term in the error function can be made better without making another worse (the so-called Pareto front). Then we still have to make a choice as to which point along this curve we want to operate at.
Currently, I am unable to engage the coil-dewhitening filters without destroying cavity locks. One reason why this is so is because the present Oplev servos have a roll-off at high frequencies that is not steep enough - engaging the digital whitening + analog de-whitening just causes the DAC output to saturate. Today, Rana and I discussed some ideas about how to approach this problem. This elog collects these thoughts. As I flesh out these ideas, I will update them in a more complete writeup in T1700363 (placeholder for now). Past relevant elogs: 5376, 9680.
Before the CDS went down, I had taken error signal spectra for the ITMs. I will update this elog tomorrow with these measurements, as well as some noise estimates, to get started.
Attachment #1 - Measured error signal spectrum with the Oplev loop disabled, measured at the IN1 input for ITMY. The y-axis calibration into urad/rtHz may not be exact (I don't know when this was last calibrated).
From this measurement, I've attempted to disentangle what is the seismic noise contribution to the measured plant output.
It remains to characterize various other noise sources.
I have also confirmed that the "QPD" Simulink block, which is what is used for Oplevs, does indeed have the PIT and YAW outputs normalized by the SUM (see Attachment #2). This was not clear to me from the MEDM screen.
GV 30 Jul 5pm: I've included in Attachment #3 the block diagram of the general linear feedback topology, along with the specific "disturbances" and "noises" w.r.t. the Oplev loop. The measured (open loop) error signal spectrum of Attachment #1 (call it y) is given by:
If it turns out that one (or more) term(s) in each of the summations above dominates in all frequency bands of interest, then I guess we can drop the others. An elog with a first pass at a mathematical formulation of the cost-function for controller optimization to follow shortly.
I came across a paper (see reference) where they have used DAOPHOT, an astronomical software tool developed by NOAO, to study the point scatterers in LIGO test masses using images of varying exposure times. I'm going through the paper now. I think using this we can analyze the MC2 images and make some interesting observations.
Reference: L.Glover et al., Optical scattering measurements and implications on thermal noise in Gravitational Wave detectors test-mass coatings Physics Letters A. 382. (2018)
I have updated the wiki with the layout of the out-of-vac optical tables: Updated optical tables
I used the new camera to take pictures.
Lesson learnt after the update:
To use the new canon to take better pictures of optics tables; set the camera to manual mode; no flash and iso at around 800 or higher if you can hold the camera still for that long. The autofocus works beautifully...so you will not need any minor tweaking of lens to take pictures.
I uploaded an updated optickle model of the upgrade to the SVN directory with the optickle models (here).
[Jenne, Suresh, with support from Jamie and Koji]
MC spots measured, MC1, MC3 no change.
No clipping going through Faraday.
Beam hitting to the right of center of PZT1. It was translated sideways so we are now hitting it on the center. Knobs adjusted so we hit center of MMT1.
Beam totally obscured by Faraday on the way to MMT2. MMT2 moved north, so that we clear the Faraday by more than a beam diameter. MMT1 knobs adjusted to hit center of MMT2.
MMT2 knobs adjusted to hit center of PZT2.
PZT2 didn't have enough range with knobs, so we loosened it, pointed then adjusted with knobs so we're hitting center of PRM.
We need to check spot centering on PRM with camera tomorrow.
Suresh checked that we're not clipped by IP ANG/POS pickoff mirrors, but we haven't done any alignment of IP ANG/POS.
Tomorrow: Open ITMX door. Check with Watek that we're hitting center of PRM. Then look to see if we're hitting center of PR2. Then, continue through the chain of optics.
Gouy not Guoy:
pronounced Goo-eee, with the emphasis on the second syllable.
It's OK; even Siegman got it wrong---48 times.
RA: NO, stil not OK.
Yesterday, I moved the following optics:
After moving these components around a bit, I locked them down once I was happy that the beam was pretty well centered on both of them, and also on AS110 and AS55 (measured using O'scope with single bounce from one ITM, other optics misaligned).
The beam was close to clipping on the lens mentioned in #1, probably because this wasn't checked when the 90-10 BS was installed for the AUX laser. Furthermore, I believe we are losing more than 10% of the light due to this BS. The ASDC (which is derived from AS55 PD) level is down at ~110cts as the Michelson is fringing, while it used to be ~200 cts. I will update with a power measurement shortly. But I think we should move ahead with the plan to combine the beam into the IFO's AS mode as discussed at the meeting last week.
Unrelated to this work, but c1psl and c1iscaux were keyed.
ASDC has something weird going on with it - my main goal yesterday was to calibrate the actuators of ITMX, ITMY and BS using the Michelson. But with the Michelson locked on a dark fringe, the ASDC level changed by up to 50 counts seemingly randomly (bright fringe was ~1000 cts, I had upped the whitening gain to +21dB), even though the CCD remained clearly dark throughout. Not sure if the problem is in the readout electronics or in the PD itself.
Furthermore, I believe we are losing more than 10% of the light due to this BS. The ASDC (which is derived from AS55 PD) level is down at ~110cts as the Michelson is fringing, while it used to be ~200 cts. I will update with a power measurement shortly. But I think we should move ahead with the plan to combine the beam into the IFO's AS mode as discussed at the meeting last week.
Is the 10% specified for P-Pol or for UNP? I contacted CVI about beamsplitters, since their website doesn't list a BS1-1064-90-... option on the website. They say a R=90% beamsplitter would be a custom job. The closest stock item they got is BS1-1064-95-2025-45UNP specified at R=95% for UNPolarized beams. They were kind enough to sent me the measured transmission curves for a recent lot of these, which is attached was uploaded to the wiki [Elog Police K: NO PROPRIETARY DOCUMENTS ON THE ELOG, which is public. Put it on our wiki and put the link here]. The figure is not labeled, but according to the contact Red is S-Pol and Blue is P-Pol, which means that this one actually has R=~90% for P, pretty much what we want. We'll need to buy two of these to make the swap in the setup.
Back to your original point: There's only a BS1-1064-10-2025-45UNP on the website, so unless we got these as custom items, the R for P-Pol is probably NOT actually 10%, just somewhere between 0% and 20%
Of course, many (but no all) of the optics were custom-ordered back in ~2000.
4 std cataloge item fused silica BS1-1064-95-2025-45UNP
ordered today. They will arrive no later than July 13, 2018
Jenne asked me to simulate the signals on POP QPD when moving different mirrors, as a function of the Gouy phase where the QPD is placed.
I used the opportunity to create a MIST simulation file of the entire 40m interferometer, essentially based on my aLIGO configuration file. I used the recycling cavity lengths obtained from our survey, and other parameters from the wiki page. The configuration file is attached (fortymeters.mist).
Coming back to the main simulation, here is the result, both for the "regular" POP QPD and for a 22MHz demodulated one. The Gouy phase is measured starting from PR2. Cavity mirrors are easily decoupled from PRM in the "regular" QPD. As already demonstrated in a previous simulation, ETMs signals are very small in the 22 MHz QPD. Moreover, it is possible to zero the contribution from ITMs by choosing the right Gouy phase, at the price of a reduction of the PRM signal by a factor of 3-4. Simulation files are attached.
# Configuration file for full dual recycled 40m interferometer
# General parameters
const Pin 1 # input power
# Mirror parameters
const T_ITM 0.01384 # ITM transmission [from https://wiki-40m.ligo.caltech.edu/Core_Optics]
# Configuration file for full dual recycled 40m interferometer
# General parameters
const Pin 1 # input power
# Mirror parameters
const T_ITM 0.01384 # ITM transmission [from https://wiki-40m.ligo.caltech.edu/Core_Optics]
% compile and create simulation class
s = FortyMetersPOP_QPD(4);
% set angular motion of ITMs, ETMs and PRM
Over the past few days, I've been thinking about how to workout the details conerning Rana's request about a 'map' of the vicinity of the 40m interferometer. This map will take the positions of N randomly placed seismic sensors as well as the signals measured by each one of them and the calculated cross correlations between the sensors and between the sensors and the test mass of interest to give out a displacement vector with new sensor positions that are close to optimum for better seismic (and Newtonian) noise cancellation.
Now, I believe that much of the mathematical details have been already work out by Jenne in her thesis. She explains that the quantity of interest that we wish to minimize in order to find an optimal array is the following,
where is the cross-correlation vector between the seismic detectors and the seismic (or Newtonian) noise, is the cross-correlation matrix between the sensors and is the seismic (or Newtonian) noise variance.
I looked at the paper that Jenne cited from which she obtained the above quantity and noted that it is a bit different as it contains an extra term inside the square root, it is given by
where the new term, is the matrix describing the self noise of the sensors. I think Jenne set this term to zero since we can always perform a huddle test on our detectors and know the self noise, thus effectively subtracting it from the signals of interest that we use to calculate the other cross correlation quantities.
Anyways, the quantity above is a function of the positions of the sensors. In order to apply it to our situation, I'm planning on:
1) Performing the huddle tests on our sensors, redoing it for the accelerometers and then the seismometers (once the data aquisition system is working... )
2) Randomly (well not randomly, there are some assumptions we can make as to what might work best in terms of sensor placement) place the sensors around the interferometer. I'm planning on using all six Wilcoxon 731A accelerometers, the two Guralps and the STS seismometer (any more?).
3) Measure the ground signals and use wiener filtering in order to cancel out their self noises.
4) From the measured signals and their present positions we should be able to figure out where to move the sensors in order to optimize subtraction.
i have also been messing around with Jenne's code on seismic field simulations with the hopes of simulating a version of the seismic field around the 40m in order to understand the NN of the site a little better... maybe. While the data aquisition gets back to a working state, I'm planning on using my simulated NN curve as a way to play around with sensor optimization before its done experimentally.
i have as well been thinking and learning a little bit about source characterization through machine learning methods, specially using neural networks as Masha did back in her SURF project on 2012. I have also been looking at Support vector machines. The reasons why I have been looking at machine learning algorithms is because of the nature of the everchanging seismic field around the interferometer. Suppose we find a pretty good sensor array that we like. How do we make sure that this array is any good at some time t after it has been found? If the array mostly deals with the usual seismic background (quiet) of the site of interest, we could incorporate machine learning techniques in order to mitigate any of the more random disturbances that happen around the sites, like delivery trucks, earthquakes, etc.
An exercise of optimally subtracting one seismometer signal by another using weiner filters was done. Results have been summarized document attached.
The new HAM-A coil drivers have a single DB9 connector for all the binary inputs. This requires that the dewhitening switching signals from the fast system be spliced with the coil enable signals from c1auxey. There is a common return for all the binary inputs. To avoid directly connecting the grounds of the two systems, I have looked for a suitable opto-isolator for the c1auxey signals.
I best option I found is the Ocean Controls KTD-258, a 4-channel, DIN-rail-mounted opto-isolator supporting input/output voltages of up to 30 V DC. It is an active device and can be powered using the same 15 V supply as is currently powering both the Acromags and excitation. I ordered one unit to be trialed in c1auxey. If this is found to be good solution, we will order more for the upgrades of c1auxex and c1susaux, as required for compatibility with the new suspension electronics.
I have received the opto-isolator needed to complete the new c1auxey system. I left it sitting on the electronics bench next to the Acromag chassis.
Here is the manufacturer's wiring manual. It should be wired to the +15V chassis power and to the common return from the coil driver, following the instructions herein for NPN-style signals. Note that there are two sets of DIP switches (one on the input side and one on the output side) for selecting the mode of operation. These should all be set to "NPN" mode.
As Jon wrote we need to use the NPN configuration (see attachments). I tested the isolator channels in the following way:
1. I connected +15V from the power supply to the input(+) contact.
2. Signal wire from one of the digital outputs was connected to I1-4
3. When I set the digital output to HIGH, the LED on the isolator turns on.
4. I measure the resistance between O1-4 to output(-) and find it to be ~ 100ohm in the HIGH state and an open circuit in the LOW state, as expected from an open collector output.
Unlike the Acromag output, the isolator output is not pulled up in the LOW state. To do so we need to connect +15V to the output channel through a pull-up resistor. For now, I leave it with no pull-up. According to the schematics of the HAM-A Coil Driver, the digital output channels drive an electromagnetic relay (I think) so it might not need to be pulled up to switch back. I'm not sure. We will need to check the operation of these outputs at the installation.
During the testing of the isolator outputs pull-up, I accidentally ran a high current through O2, frying it dead. It is now permanently shorted to the + and - outputs rendering it unusable. In any case, we need another isolator since we have 5 channels we need to isolate.
I mounted the isolator on the DIN rail and started wiring the digital outputs into it. I connected the GND from the RTS to output(-) such that when the digital outputs are HIGH the channels in the coil driver will be sunk into the RTS GND and not the slow one avoiding GND contamination.
- Could you explain what is the blue thing in Attachment 1?
- To check the validity of the signal chain, can you make a diagram summarizing the path from the fast BO - BO I/F - Acromag - This opto-isolator - the coil driver relay? (Cut-and-paste of the existing schematics is fine)
I made a diagram (Attached). I think it explains the blue thing in the previous post.
I don't know what is the grounding situation in the RTS so I put a ground in both the coil driver and the RTS. Hopefully, only one of them is connected in reality.
I mounted the optoisolator on the DIN rail and connected the 3 first channels
to the optoisolator inputs 1,3,4 respectively. I connected the +15V input voltage into the input(+) of the optoisolator.
The outputs were connected to DB9F-2 where those channels were connected before.
I added DB9F-1 to the front panel to accept channels from the RTS. I connected the fast channels to connectors 1,2,3 from DB9F-1 to DB9F-2 according to the wiring diagram. The GND from DB9F-1 was connected to both connector 5 of DB9F-2 and the output (-).
I tested the channels: I connected a DB9 breakout board to DB9F-2. I measured the resistance between the RTS GND and the isolated channels while switching them on and off. In the beginning, when I turned on the binary channels the resistance was behaving weird - oscillating between low resistance and open circuit. I pulled up the channels through a 100Kohm resistor to observe whether the voltage behavior is reasonable or not. Indeed I observed that in the LOW state the voltage between the isolated channel and slow GND is 15V and 0.03V in the HIGH state. Then I disconnected the pull up from the channels and measured the resistance again. It showed ~ stable 170ohm in the HIGH state and an open circuit in the LOW state. I was not able to reproduce the weird initial behavior. Maybe the optoisolator needs some warmup of some sort.
We still need to wire the rest of the fast channels to DBF9-3 and isolate the channels in DBF9-4. For that, we need another optoisolator.
There is still an open issue with the BI channels not read by EPICS. They can still be read by the Windows machine though.
This RTS also use the BO interface with an opto isolator. https://dcc.ligo.org/LIGO-D1002593
Could you also include the pull up/pull down situations?
Since this Ocean Controls optoisolator has been shown to be compatible, I've gone ahead and ordered 10 more:
They are expected to arrive by Wednesday.
According to the BO interface circuit board https://dcc.ligo.org/D1001266, PCIN wires are connected to the coil driver and they are not pulled either way.
That means that they're either grounded or floating. I updated the drawing.
I checked the BI situation on the HAM-A coil driver. It seems like these are sinking BIs and indeed need to be isolated from the Acromag unit GND to avoid contamination.
The BIs will have to be isolated on a different isolator. Now, the wires coming from the field (red) are connected to the second isolator's input and the outputs are connected to the Acromag BI module and the Acromag's RTN.
I updated the wiring diagram (attached) and the wiring spreadsheet.
In the diagram, you can notice that the BI isolator (the right one) is powered by the Acromag's +15V and switched when the coil driver's GND is supplied. I am not sure if it makes sense or not. In this configuration, there is a path between the coil driver's GND and the Acromag's GND but its resistance is at least 10KOhm. The extra careful option is to power the isolator by the coil driver's +V but there is no +V on any of the connectors going out of the coil driver.
I installed an additional isolator on the DIN rail and wired the remaining BOs (C1:SUS-ETMY_SD_ENABLE, C1:SUS-ETMY_LR_ENABLE) through it to the DB9F-4 feedthrough. I also added DB9F-3 for incoming wires from the RTS and made the required connection from it to DB9F-4.
I tested the new isolated BOs using the Windows machine (after stopping Modbus). As before, I measure the resistance between pin 5 (coil driver GND) and the channel under test. When I turn on the BO I see the resistance drops from inf to 166ohm and back to inf when I turn it off. Both channels passed the test.
If my understanding is correct, the (photo receiving) NPN transistor of the optocoupler is energized through the acromag. The LED side should be driven by the coil driver circuit. It is properly done for the "enable mon" through 750Ohm and +V. However, "Run/Acquire" is a relay switch and there is no one to drive the line. I propose to add the pull-up network to the run/acquire outputs. This way all 8 outputs become identical and symmetric.
We should test the configuration if this works properly. This can be done with just a manual switch, R=750Ohm, and a +V supply (+18V I guess).